1. Field of the Invention
The invention relates to a process for preparing cooked rice in aseptic package made of long grain rice with excellent fluffiness. More particularly, the invention relates to a process for preparing cooked rice in aseptic package prepared by a process comprising soaking long grain rice in solution of emulsified oil, filling the rice automatically in a heat resisting plastic container, sterilizing the rice 4˜10 times repeatedly for 4˜8 seconds at high temperature of 130˜150° C. and high pressure, cooking said sterilized long grain rice in a measured amount of liquid under fixed conditions, and packaging the resultant cooked rice in aseptic so that cooked rice which is free from microorganism and capable of long term preservation (more than 6 months) can be obtained.
2. Description of the Prior Art
Rice grain is classified into four types based on its length and width by International Rice Research Institute (IRRI). According to classification by IRRI, extra long grain is more than 7.51 mm long, long grain is 6.61˜7.5 mm long, medium grain is 5.51˜6.60 mm long, and short grain is less than 5.50 mm long. And according to classification by FAO, extra long grain is more than 7.0 mm long, long grain is 6.0˜6.99 mm long, medium grain is 5.0˜5.99 mm long and short grain is less than 5.0 mm long. The grain shape refers to the grain length to width ratio and is categorized as slender (ratio more than 3.0), medium (ratio between 2.0˜3.0), round (ratio less than 2.0).
It is long grain produced most in the world and long grain is typically “Indica Rice”, which has much fluffiness and is crumbly when cooked. So, the rice is not suitable for staple food (in Korea, Japan or China etc) but suitable for one-dish meals for example curried rice and omelet rice. It is mainly produced in Philippine, Indonesia, China areas south of the Yangtze River and South America (Arkansas, Louisiana).
Medium grain and short grain have similar characteristics and they are typically “Japonica Rice”, produced in Korea, Japan, Italy, America California and Egypt, which have much glutinousness.
In general, rice is composed of 90% starch, 7.9% protein and small amount of lipids. Rice starch is amylose and amylopectin. Japonica rice contains 15˜17% of amylose, while Indica rice contains 25˜27% of amylose, that means less amylose result in much glutinousness.
Long grain has high amylose content and thick cell membrane of starch, which causes no destruction of cell wall during cooking. Therefore, cooked rice using long grain has much fluffiness and it is not suitable for Korean's taste. But the majority of rice varieties produced and used are long grain.
When cooked rice in aseptic package is produced by the method disclosed by the Korean patent application No. 1996-062376, it shows many differences in quality, compared to cooked rice produced at home by general method. The property of long grain not having glutinousness but having fluffiness doesn't remain on cooked rice in aseptic package. It results from destruction of starch cell membrane and pasting of starch during sterilization at high temperature and high pressure.
U.S. Pat. No. 6,139,898 describes a process for producing cooked rice keeping fixed water content by coating rice surface with oil.
Generally, cooked rice is prepared by a process comprising adding measured amount of water to rice and heating at about 100° C. for about more than 30 min. About 102˜104 cfu/g of microorganisms exist on surface of rice. And general cells of microorganism are destructed but heat-resisting spore are not destructed perfectly. Such propagation of heat-resisting microorganism is a serious problem in long-term preservation of cooked rice at room temperature.